In many instances, an internal combustion engine installed in a machine, such as a vehicle, ship, farming equipment, motor generator, or the like, is provided with a control device that uses a microprocessor to control particular components, such as machinery, belonging to the internal combustion engine. In a control device of this kind, a power source is necessary for operation of the microprocessor. Moreover, in cases in which a component to be controlled lacks a power source, it is necessary to supply a power source to the component to be controlled. Furthermore, in some cases, power is necessary for the operation of sensors as well.
In a case in which the generator attached to an internal combustion engine is a magnet generator of internal magnet type, provided with a rotor having a multitude of magnetic poles constituted by permanent magnets on the inside periphery of a fly wheel, and a stator having a constitution in which a plurality of magneto coils are wound onto a multipole armature core having magnetic pole sections opposing the magnetic poles of the rotor to the inside of the flywheel, and having, in addition to an ignition device-driving magneto coil for supplying power to the ignition device of the internal combustion engine, a load-driving magneto coil that produces surplus output, the microprocessor and the load to be controlled can be supplied with sufficient power by the output of the magnet generator. However, in a case in which, for the purpose of cost reduction or of smaller size/lighter weight of the engine, the generator attached to the engine is provided only with an ignition device-driving magneto coil, or in a case in which, despite being provided with an additional magneto coil, the additional magneto coil has a large load so as to produce no surplus output, it has sometimes proved difficult to supply sufficient power to the microprocessor and the load to be controlled.
Particularly when an ignition device-specific magnetic generator like that shown in Patent Document 1, which is provided with a rotor in which a single permanent magnet is attached to the outside periphery of a flywheel attached to the crankshaft of the internal combustion engine and in which are constituted three magnetic poles; and a stator in which a magneto coil for generating voltage to supply ignition energy to the ignition device of the internal combustion engine has been wound onto a core having magnetic pole sections opposing the magnetic poles of the rotor (herein, this type of magnet generator is termed an external magnet type magnet generator) is employed as the magnet generator installed in an internal combustion engine, it is problematic to ensure a power source for supplying power to the microprocessor and the like.
In an external magnet type magnet generator, alternating current voltage of a waveform having a first half wave voltage of one polarity, a second half wave voltage of another polarity generated following this first half wave voltage, and a third half wave voltage of the one polarity generated following this second half wave voltage, is generated once during each one revolution of the crankshaft. For reasons having to do with the structure of the rotor, the second waveform voltage is the voltage having the highest crest value among the first to third half waves generated by the external magnet type magnet generator, and therefore this second waveform voltage is employed for driving the ignition device of the internal combustion engine.
In some cases, the magneto coil of an external magnet type magnet generator is provided as the primary coil of the ignition coil constituting the internal combustion engine ignition device, and in other cases is provided as a separate magneto coil from the ignition coil. In a case in which the magneto coil of an external magnet type magnet generator is the primary coil of the ignition coil, in many instances, an ignition unit provided with constituent elements constituting the ignition coil as well as an ignition circuit, and constituent elements of an ignition control device for controlling the ignition circuit, is provided in an integrated state to the ignition coil provided to the stator.
In the above-described manner, in a case in which the generator attached to an internal combustion engine is an external magnet type magnet generator, because the generator is provided only with a magnetic coil for driving the ignition device, power is not supplied by the magnet generator to any load other than the ignition device. While it would be conceivable for the first half wave voltage and the third half wave voltage of identical polarity which are output before and after the second half wave voltage (the voltage for driving the ignition device) by the external magnet type magnet generator, to be utilized as voltages for driving a load besides the ignition device, for reasons having to do with the structure of the rotor, the crest values of the first half wave voltage and the third half wave voltage cannot be set very high, and therefore it is difficult using only these voltages to supply sufficient power to a microprocessor and a load to be controlled. Additionally, while it would be conceivable to utilize the second half wave voltage, which is employed for operating the ignition device, to supply power to a microprocessor and a load to be controlled, in a case in which such a constitution is adopted, there is insufficient energy to drive the ignition device, thereby making a decline in ignition performance unavoidable.
For this reason, in cases in which it is necessary to use a microprocessor to control specific machinery, other than the ignition device, which is to be controlled in an internal combustion engine, it was necessary to either prepare a battery of sufficient power capacity as a separate power source, as shown in Patent Document 2; or to employ as the generator attached to the internal combustion engine a large and expensive magnet generator of internal magnet type provided, in addition to the magneto coil for driving the ignition device, with a magneto coil capable of producing surplus output.